How do you describe the end behavior of f(x)=x^2-8x+18f(x)=x28x+18?

1 Answer
Sep 29, 2016

as xrarr-oo, f(x)rarr+oox,f(x)+ and
as xrarr+oo, f(x)rarr+oox+,f(x)+

Explanation:

f(x)=color(red)1x^color(blue)2-8x+18f(x)=1x28x+18

Because the degree color(blue)22 is even, this an even function. Even functions have end behaviors that both go in the same direction in y.

The function has a positive leading coefficient, color(red)11. Even functions with positive leading coefficients have end behaviors that both go toward positive infinity (both ends of this quadratic/parabola graph point "up").

In other words,

as xrarr-oo, f(x)rarr+oox,f(x)+ and
as xrarr+oo, f(x)rarr+oox+,f(x)+